The present invention relates to an ultrasonic wave pump, or an ultrasonic wave nebulizer for converting liquid water to mist, in which an ultrasonic wave vibration by a piezoelectric vibrator element operates as both a pump for the suction of water, and for nebulizing water.
We have proposed an ultrasonic humidifier for converting water to mist. U.S. Pat. No. 4.338 576 is one of the examples. In the prior humidifier, an ultrasonic vibrator made of piezoelectric ceramics is bottom mounted and partially submerged in water which is atomized upon vibration of the ceramics, and an electric fan blows creating mist. Therefore, it must have not only an ultrasonic vibrator, but also a fan which has a mechanical rotation member. Further, a tank for mounting water must have the particular structure for securing an ultrasonic vibrator.
Another structure for an ultrasonic pump is proposed in the Japanese patent application No. 309113/86 by our company, as indicated in FIG. 1.
In FIG. 1, the numeral 1 is an elongated main body having a first horn 4 for amplifying vibration, and a circular inlet 5 at the bottom of the body . The body 1 has also a second horn 30 for amplifying vibration, and a circular outlet 31 at the top of the body 1. The horn portions 4 and 30 are thinner than other portions of the main body so that the vibration in the main body is amplified in the thinner portion. The middle portion of the body 1 has male screw portions 2 and 3. The body 1 has also an elongated through hole 6 at the center of the main body 1, allowing for the passage of water. The bottom opening of the through hole 6 is at the center of the circular inlet 5, and the top opening of the through hole 6 is at the center of the circular outlet 31.
A circular flange 8, a circular first electrode 9A, a circular first piezoelectric vibrator 10A, a circular second electrode 9B, a circular second piezoelectric vibrator 10B, a circular third electrode 9C, a washer 12, and a plate spring 13 are penetrated by the main body 1, and those penetrated members are fixed to the main body 1 by a pair of nuts 11A and 11B which engage with the male screw portions of the main body 1.
When the water surface P is in the range Q, and the bottom inlet 5 is in the water, the vibrators 10A and 10B vibrate (thickness vibration) by applying high frequency voltage across the electrode 9B and the electrodes 9A and 9C. The vibration is amplified at the horn 4 which is thinner than the middle portion, and then, the ultrasonic vibration in the direction indicated by the arrow R is provided at the inlet 5.
Then, water is pumped up along the arrow S into the through hole 6. The water thus raised reaches the top of the main body 1, and vibrates violently at the top surface of the outlet 31, then, the water at the top surface of the outlet 31 is converted to mist which dissipates in the air.
The structure of FIG. 1 was intended to be used in an air-conditioner for nebulizing drain water into the air.
However, we realized the disadvantages of the structure of FIG. 1 in our research test as follows.
First, when the structure is supported by using the flange 8 which is located under the vibrators, the flange 8 itself vibrates, therefore, the vibration is not sufficiently sent through the water.
Secondly, since the structure is not water-proof, when there is an overabundance of water, the vibrators 10A and 10B are dipped in water. Additionally, the mist is then converted again to water, which flows downwardly to wet the vibrators 10A and 10B.
Another disadvantage is the diameter of the inlet 5 and the outlet 31. For manufacturing reasons, it is preferable that the diameter of the inlet and the outlet are equal to or less than the diameter of the middle portion of the main body, since the nuts 11A and 11B must pass the inlet and the outlet when the structure is assembled. On the other hand, for operational reasons, it is preferable that the diameter of the inlet and the outlet be larger than the diameter of the middle portion of the main body so that the nebulizing operation is carried out efficiently. Since a prior structure has an integrated structure, it was impossible to meet with these two requirements.